What do you think is a sufficient number of words in order to understand Latin?
I've been making flash cards for a week, with the nominative on one side and the declensions on the other. I've memorized 70 so far.

There's some discussion in this thread, including a link I posted to an interesting list of the "most important" words. The bottom line seems to be: about 1500 words or so. Of course, you can start reading Latin much sooner. Each author tends to have his favourite vocabulary.

Ulpianus is right, but do not have too high expectations... the occasional (or frequent) glance at the dictionary should be expected far into your reading experiences. Just about any beginner's books will supply you with a good foundation on the most common words and then you will assimilate more from reading or studying. Just memorizing words out of context is not always the best idea. It is generally agreed upon to be more efficient to use those words right after you learn them, or else memorize them by reading in a context.